Cyanobacteria warning for Nashua River

NASHUA – Those planning activities in the Nashua River near Mine Falls Park beware: bacteria that can cause nausea, seizures and central nervous system damage are lurking in the water.

The New Hampshire Department of Environmental Services has issued a cyanobacteria warning for this portion of the river. Samples collected last week showed millions of cells of Oscillatoria accumulating in this region of the river.

As a result, officials are warning those who use the body of water. This warning is intended as a precautionary measure for short-term exposure, rather that being based on toxin evaluations. Nonetheless, officials advise people to avoid contact with the water in areas showing elevated cyanobacteria cell conditions and to keep pets out of any waters that are experiencing a cyanobacteria bloom.

“It’s very likely, with it being a river, it moved on,” department Beach Program Coordinator Amanda McQuaid said. “This is sort of a late advisory, but because we’re going out on Friday, we wanted to keep the word out until we can confirm it has dissipated from the water.”

In the meantime, park users should avoid contact with the water in areas where the surface has scum, green streaks or blue-green flecks aggregating along the shore.

McQuaid said this really isn’t necessarily a closure, so much as it is a warning to just let people know not to touch it along the shoreline, and especially to keep their pets out of the water. She said NHDES discovered the cyanobacteria as part of a routine inspection with the aquatic plants group.

“They were down by, I believe right above the falls basically, sort of at the corner where the Nashua River is,” McQuaid said. “They said it was a pretty good length, several hundred feet, and just sort of accumulating where people were fishing. The sample I looked at was very concentrated with this type of Oscillatoria, in the millions.”

According to the U.S. Environmental Protection Agency, cyanobacteria were previously known in some circles as blue-green algae. The modern scientific definitions of algae and bacteria led to the name change.

McQuaid said with this specific type, it can accumulate to the millions pretty quickly, but NHDES is unsure of where it originated because the water is moving down the river.

Officials routinely monitor public beaches and waters of the state for cyanobacteria throughout the summer. Once a warning or advisory is issued, they return to the affected bodies of water on a weekly basis until the cyanobacteria standards are once again met.

Cyanobacteria are natural components of water bodies around the world, but blooms and surface scums can form when excess nutrients are available to the water. Some cyanobacteria can produce toxins, which are stored within the cells, but released when the cell dies and those toxins can lead to both acute and chronic health effects.

McQuaid said officials do not get a lot of reports for cyanobacteria exposure, but said health effects can vary, and that it really affects dogs quickly. According to NHDES, acute health effects include irritation of skin and mucous membranes, tingling, numbness, nausea, vomiting, seizures and diarrhea. Chronic effects would then include liver and central nervous system damage.

“We’re due to go back on Friday,” McQuaid said. “So, we just issued an advisory because the most recent observation was pretty significant.”

Adam Urquhart can be reached at 594-1206 or